Veneer molding process



Nov. 6, 19 45. c. u. sRAMELsAcHE 22,687 I VENEER MOLDING PROCESS Original Filed Aug. 11, 1939 4 Sheets-Sheet 1 Jwum i-wu CLARENCE U.GRAMEL$PHCHER,

Nov. 6, 1945. c. u. GRAMELSPACHER 22,587 Y VENEER momma PROCESS Original Filed Aug. 11, 1939 4 sheets-sheet 2 I 7 igmnsuc: usmmsmmcnsn,

Nov. 6, 1945. c.- u. GRAMELSPACHER 22,537

VENEER MOLDING PROCESS .7 Ori inal Filed Aug. 11. 19:59 4 sheets-sheet 3 J. A I d 4 Jan/um YCLRRENC: U-GRAMELPAHER,

' W1 sQM Nov. 6, 1945. c. u. GRAMELSPACHER VENEER MOLDING PROCESS' Original Filed Aug. 11. 19:59

4 Sheets-Sheet 4 4 Jrw CLARENCE U. GRHMELSPA M: CH5 R,

Reissued Nov. 6, 1945 VENEER MOLDING PROCESS Clarence U. Gramelspacher, Jasper, Ind., assignor to Jasper Wood Crafters, Inc., Jasper, Ind., a corporation of Indiana Original No. 2,312,332, dated March 2, 1943, Se-

rial No. 289,697, August 11, 1939. Application for reissue February 14, 1945, Serial No. 577,745

6 Claims.

This invention relates to a process for forming individual sheets of wood veneer or of very flexible plywood (say .2 or 3-ply) into articles of desired configuration" and moreparticularl to a process of forming said sheets into articles embodying simple or compound curves. The present invention eliminates the necessity for first making a flat sectionof plywood and then bending it into the desired shape by saw-kerfing, corrugating and the like. the present invention relates to a veneer molding process wherein pressure is exerted on the outside of the sheets to be joined and forming pressure is yieldingly exerted from the inside of the sheets outwardly as by means of an expansible bag. Pressure of any kind can be used for these purposes.

The principal object of the present invention is to devise a method of forming veneer or flexible plywood sheets which are free to slide relative to one another by exerting pressure outwardly from inside of-the sheets, while holding the sheets from their exterior in such manner that the inwardly exerted pressure is eilective; the pressure exerted from the outside, cooperates with the pressure exerted from the inside to produce an article the configuration of which corresponds exactly to that of the outer mold member so that the shape and dimensions of the v article are accurately known in advance.

Another object is to carry out a process of the foregoing type wherein the inner mold member is in the form of an expansible bag member which is expanded evenly outwardly over the entire inside area of the sheets to be formed by means of a fluid under pressure admitted thereto, such as steam, air or other gas under pressure, or a liquid such as water, .oil, or other suitable hydraulic liquid under pressure.

'Another object, is to devise a process of the type above set forth wherein at least one of each pair of adjoining surfaces of the sheets of veneer or thin plywood isprecoated with an adhesive which is either liquid at the time of assembly or which becomes liquid under the conditions of molding; this liquid adhesive acts as a lubricant allowing the individual sheets to slide relative to one another, this shifting enabling the quick formation of a more perfect article wherein none of the individual sheets is under stress or tension relative to any other sheet,- absolute concentricity throughout the curves being obtained.

. Yet another object is to carry outa process of thetype described above wherein heat is applied to the sheets during the molding process in In a still more particular aspect,

order to dry and harden the glue or to set the resin where a thermo-setting resin adhesive is employed; this heat maybe applied to the sheets from either the outside or the inside; a convenient method is to employ cored outer mold members and to pass a suitable hot fluid under pressure into the expansible bag to serve the dual purpose of expanding the same to shape the article and to heat the sheets constituting the article, 7

Another object is to carry out a process of the foregoing type wherein a base member connects the ends of the veneer or plywood sheets.

Another object is to provide an expansible bag of variable thicknessor consistency so that when pressure is exerted against the inside of the clamping form this pressure will be exerted evenly over the entire area; for example, if a spherical bag is used in a rectangular article the pressure on the corners will not beas great as the pressure on the sides; however, I have discovered that this effect can be compensated for to a large extent by designing the bag so that the portions for contacting the sides are relatively thick andprogressively thin out to the portions which contact the corners. I Another object is to devise apparatus for, carrying out the foregoing process. 7

Another object is to devise a method and apparatus for molding internally irregularly, shaped articles which involves utilization of a rigid mold member contacting on one side the irregular surface, such as an internal insert, and on the other side, which is smooth, the expansible bag.

Other objects will more, fully hereinafterappear. I In the accompanying drawings: Figure 1 is a perspective showing the individual sheets of veneer, or single laminations, with the coating of adhesive on at least one face of each, ready for molding. Instead of coating each lamination, alternate laminations may be coated on both sides. v

Figure 1a is vertical section through one of the coated veneer sheets of Figure 1. Figure 2 is a perspective showing individua sheets of coated plywood, ready to be molded.

Figure 2a is a vertical section through a coated plywood sheet of Figure 2. I Figure 3 is a horizontal section through a mold for a four-sided radio cabinet, as an example, having a baseboard and shows the individual veneer shets in place with the outer mold members about to .be clamped about them and with the expansible rubber bag inner mold member in collapsed form. :The showing of. a radio cabinet is merely an example of an article which can be molded by this process.

Figure 4 is a horizontal section on the line 44 of Figure 5, looking in the direction of the arrows, and shows the mold of Figure 3 closed and the bag expanded; the bag is shown as thinned in those areas where expansion is most extensive.

Figure 5 is a vertical, transverse section on the line 5-5 of Figure 4, looking in the direction of the arrows; in this figure the article has been completely formed, the mold cover opened, the cabinet front has been inserted on the-top thereof, and the mold cover has'been closed to cement the front in place; this figure shows the inlet to the expansible bag inner mold member and the guide for the outer front wall :01 the mold; this shows merely one way of applying the front of the cabinet.

.Figure 6 is a horizontalsectional view of a modification in which no baseboard is employed:

' the ends of each veneer sheet form a butt joint Figure '9 'is a horizontal section showing a '35 modification in which an insert extends inwardly fmm'the inner .face of the article causing sharp internal angles, a rigid auxiliar mold member "being provided to present "a smooth face to the :expansible bag and to transmit the pressure thereof "evenly to the insert 'tion of the article.

.Figure 10 is a perspective view showing the laminations of 'veneer cut for a still further modification; this view is also an example of 45 the procedure wherein alternate laminations are adhesively coated on both sides and the other alternate laminations are uncoated.

Figure "11 is a vertical sectional 'view through themiddle lamination of Figure .10.

Figure 12 :is a vertical sectional view similar to "Figurefi, showing the preparation "of an "article such as a five-sided article from the fiat individualsheets of Figure 10.

Referring first to Figures B to 5 of the drawings, reference numeral designates a supporting base for .themdlding device. To base I is attached by means of "bolts 5 a vertical rear'wall 2 which 'is stationary "and forms a rear mold 'member. Hinged to :rear wall 2 by means "of "hinges 3 are end walls l "which are adapted to be swung outwardly until parallel withrear wall 2, or even further if desiredgto allow the lamination assembly to b einserted in themold. A front mold wall *6 is 's'lidabl mounted on base I :by means of 'aplurality of elongated pins 'Iprojecting upwardly from and integral with base I (see Figure 5) and which are received within slots '8 in the bottom of wa1l6. Slots '8 are elongated in the direction in which 'Iront wall 15 is slidable.

Front wall '5 is provided on its inward facewith an outward recess 43 to receive the baseboard I5 .01 the exemplary radio cabinet or other object to be molded. LFron't wall 6 and rear wall! are mold members 9 which may integral with the walls and which serve to impart the desired curved configuration to the corners of the cabinet. Front wall 6, rear wall 2 and end walls 4 are provided with cored passageways II which are adapted to be supplied withsteam or other hot. fluid by an inlet pipe lil) ffor the purpose of heating the laminations during molding. Any suitable means (not shown) such as a resilient gasket may be provided to seal the passages II at the point where they interconnect between ad ,jacent mold walls.

,A mold cover 12 hinged at l3 to rear wall 2 is "adapted to be clamped down over the closed mold preparatory to molding and locked in its clamped position by'means oflinks l4 pivoted to the forward edge of cover l2 adapted to be looked over hook members 16 fixedly mounted on the front face of .front wall 6 by hand locking members I! pivotally carried on the lower end of links J4.

Front wall 6 is adapted to Ibemoved inwardly into clamping position againstthe ends 18 of inwardly swung end walls :4 thereby clamping the end walls 4 tightlybetweenrear wall 2 and front wall 6. To this end, a cam clamping member 1|9 having a handle 2| is pivoted about a vertical pivot member!!! fixedlymounted in base "I. Cam

member 19 is adapted to engage the front face of front wall '6 and to urge wall 6 inwardly into 'a firmly clamped'position and to lock it in this position and to lock it in this position by reason of the frictional engagement of earn 1! with wall *6.

End walls '4 are "adapted to be locked in their inward position by means "of circular heads 22 journalled on the upper ends 'of shanks 23 which extend downwardly -(see Figure '1) through elongated curved slots 24 in base plate I intohinged engagement 2411 with a manuallyppera'ted handle '25 pivoted so as to be swingable vertically about a member 26 which is "pivoted so *as to be :swinga'ble horizontally by a pivot member "21 extending pivotally upwardly into a recess inbase plate 1. ,A circular recess 23 is "provided at the outermost end of curved slot '24 to receive cireularihea d '22 when the handle '25is atitsoutermost position so that the'top of'head '22'maybefiushwith or below the "upper surface of base "I whereby interference with outward swinging of end walls Wis prevented. A catch 29 is'provided ontheunderface ofbase 1 into which handle 25 may be insertedto lock the same in clamped position thereby locking mold walls 4 in their inward position. Tia-"unlock walls -4, handle 25 is raised vertically "out of catch "29 and is then swung outwardly and downwardly, thereby allowing walls 4 to move freely outwardly. Hinge 24a being at right anglestohandle 25 allows shank 23 to remain vertical as "handle 25 is raised" and lowered but prevents it from sliding out slot 24 due to the pressureof the'mold wall.

While mechanical means "is shown for clamping end walls 4 and front wall 15 and so designed as to give increased leverage as'the walls close in on the article to be molded, it will "be apparent that any external means for exerting clamping pressure inwardly may be employedysuchas "suitable'hydraulic-or pneumatic means. I

An expansible bag 30 of rubber or the like is provided within the mold "cavity and designed when expanded to exert pressure outwardly on the article forcing "the laminations "outwardly against the externally clamped mold members. Bag 30 has 'aninlet 31 ,which extends downwardly through base *I, and may be semi-permanently leftin themold by means o'fi'nuts '32 on inlet stem provided with inwardly extending curved c r er. 1 ag "has walls of vary "thidkness in der that it may expand into substantially the shape of the article, expanding least for the sides of the article and most for the curved corners, and more for the ends which are further apart than for the sides which are closer together. Thus the bag is quite thick at 33 for the closely adjacent sides, is of less thickness at 34 for the less adjacent ends and is of still less thickness at 35 for the curved corners. In this way, pressure is exerted evenly over the entire inner surface of the article. The same effect may be obtained by varying the stretchability of the rubber in the bag walls. Less desirably, the bag may have uniform walls of uniform consistency. The bag may preformed to approximate when collapsed the ultimate shape of the article, being slightly smaller than said ultimate shape.

Bag 30 may be inflated with any suitable fluid such as air under pressure, preferably to a pressure of 100 to 200 pounds per square inch. If it is desired to heat the article during molding, a hot fluid under pressure such as steam, or a hot liquid such as oil, diphenyl, diphenyl oxide, etc., is employed as the inflating fluid, either as the sole heating means or in addition to the employment of a heating medium in the outer mold members.

The veneer sheets indicated as 40 are precoated with a film 4| of adhesive which will act as a lubricant allowing the individual sheets to slide relative to one another during the molding. Instead of using veneer sheets, sheets 42 of flexible plywood having an adhesive coating 4| and sufficiently pliable to take the initial form may be employed (Figure 2), although the resulting article will not be quite as free of stress. Instead of precoating one side of each lamination as shown, every other lamination may desirably be coated on both faces, thereby simplifying the precoating operation. While the following description refers to using a plurality of veneer sheets 40, it will be understood that flexible plywood sheets 42 may be substituted for part or all thereof, if desired. The baseboard I is likewise initially provided with an adhesive coating 4Ia. As will be seen by comparing Figures 3 and 4, baseboard I5 is adapted to be adhesively joined during the molding to the .bottom of the completed article and to connect the ends of the plywood to form a closed article.

- In carrying out a molding operation according to Figures 3 to 5, a pre-coated baseboard I5 is placed in the recess 43 of front wall 6 and a plurality of individual pre-coated veneer sheets 40 of the same width and of gradually decreasing length are placed in the mold with their middle portions against rear mold wall 2 and their progressively inwardly shorter ends 44 projecting out at the sides of the mold. Ends 44 are then tucked into the mold into the position of Figure 3. End walls 4 are then moved inwardly and clamped at their innermost position b handles 25. Front wall 6 is then moved inwardly and clamped by means of handle 2|. Lid I2 is then moved downwardly and locked with looking members l1. Steam is then admitted to cored passageways I! through inlet It! to heat the mold, which is of metal, to the desired temperature, of say 250 to 300 F., but varying with the type of adhesive employed. Meanwhile bag 30 is inflated through inlet 3| to the desired pressure of 100 to 200 .pounds per square inch. The assembly is then allowed to stand until the adhesive has set, which will require from 2 to minutes, but here again the time required will depend on the adhesive used and the temperature employed. The bag is then deflated, the mold cover opened, and the molded cabinet removed. If desired, a cabinet front 45 (Figure 5) of sheets of veneer or plywood cut to correct shape and adhesively coated at its edges may be inserted on the formed article, the cover then closed, the bag re-inflated, and the mold allowed to stand until the front 45 is adhered. The attachment of the front of the cabinet forms no part of the present invention and may be carried out in any manner.

In Figure 6 a modification is shown wherein the mold front wall 6 is not recessed, wherein the mold is not cored for heating and wherein the four sheets of veneer 40 are each cut to the exact ultimate length forming butt joints which are staggered one on each side of the ultimate article.

In Figure 8, a modification is illustrated wherein the-veneer sheets 40 are formed into a curved article with ends at right angles and with a curved stepped portion 46. A two-part uncored mold is shown, made up of movable hinged part 48 against which molding takes place and stationary part 41 being adapted to be clamped against mold part 48 by handle 2| and cam clamp l9. Bag 30 is formed with a very thick mold portion 49 adjacent step 46 where expansion is least and with thinner portions at other portions of the article graduated in accordance with the expansion effect. As before, bag 30 exerts forming pressure outwardly on the article. Preferably, as shown, bag 30 is inflated previously to some extent before insertion and before clamping of the mold parts in order to hold the sheets 40 in place.

In Figure 9, a still further modification is shown wherein sheets of veneer cut to proper length are used and a baseboard 50 is employed which "projects inwardly so as to expose sharp edges 5| which would injure the rubber bag 30 and prevent the bag from filling the portion 52 thereadjacent. To prevent this, a metal (heat-conducting) auxiliary mold member 53 is employed which is shaped outwardly to fit insert 50 and the portions of veneer sheets 40 thereadjacent to thereby transfer pressure evenly to the article and which is smooth on its inward face to fit bag 30. In this way, the production of a perfectly formed article is insured.

In Figures 10 to 12, a still further modification is shown wherein the laminations 40a and 40b are pre-cut to form a bottom or front portion 400 and side portions 40d and end portions 40c. The intermediate lamination 40b is coated on both sides with adhesive 4| and the outer laminations 40a are uncoated. A cutout 40g is provided at each corner intersection of the sides and ends with the front to prevent the formation of an excessively compound curve at this point. The laminations are shaped into the five-sided article in the manner illustrated in Figure 12, a curved member 9a being provided along each line of bend 40;, in order to give the desired curved configuration to the corners and to prevent unduly sharp bending. As before, the outward pressure of an expansible bag 30 shapes the laminations into the final desired shape. Subsequently, the openings left between the edges of the sides 40d and the ends 40c may be filled in any desired manner as, for example, with a suitably shaped piece of wood.

It will be understood that I intend to include as within my invention such modifications as may be necessary to adapt it to varying conditions and uses and as fall within the spirit of the appended claims. For example, I may employ a thin flexible electrical heating element around the expansible bag to transmit the pressure or the bag to the article being formed w hile heat the same or may employ a metal internai mold member in a portion of the mold to transfer the pressure from the bag to the article or I may use a layer of cloth, asbestos, metal foil or the like in place of a layer of wood or in addition to the layers of wood. Similarly, while the above disclosure refers to -liquid adhesive, '1 may use any adhesive in sheet form, such as Tego g'luefilm which is a dryfilm on a verythin tissue base and which is placed between layers of veneer -rather than coated thereupon. film comprises :a phenol-formaldehyde resin which polymerizes under heat, and moisture obtained from i the veneers setting permanently after being subjected to heat for several minutes. Although such a dry film may not act as a lubricant for the veneer sheets, it does not in the least retard the sliding of the individual sheets. I may also use.

other resins on the market which are allowed to dry after being spread on the veneer in liquid term and must be thoroughly dry before pressing, these resins usually requiring solvents other than water, such as alcohol or the like. In this 1 my, I .anay avoid the use (if-aqueous liquid adhesives, the water of which may tend to swell or distort the .sheets of veneer. Whereas I have illustrated the use :of three and four laminations, I' am not limited to three or four-ply articlesjbu-t may employ any number of plies, depending upon the thickness, strength or shape required.

Having thus fully described my invention, What I claim as new and desire to secure by'Letters Patent is:

Apparatus for shaping a plurality of forming individual flexible sheets of wood into an article of predetermined configuration comprising an .outer mold adapted to have the sheets disposed therewithin in a form approximating the desired outer form of the completed product, and hold it against expanding outwardly and an inflatable member within the sheets positioned in said outer mold and adapted to exert forming pressure outwardly against said sheets, said in- Ilatable member having walls of varying thickness and disposed with the thickness of the walls inversely proportional to the extent of expansion required in order to exert evenly distributed.

forming pressure, on the portions of the sheets located at different distances from the center of the article to be formed, and means to expand said inflatable member.

2. An apparatus for shaping from a plurality of individual flexible sheets of wood an article of predetermined configuration, comprising an outer mold having a plurality of movable walls which when in closed position form an enclosed space, the opposed movable Walls providing an access opening in open position through which said sheets may be introduced into said mold space, and an inflatable member disposed within and adapted to exert forming pressure outwardly against said sheets and having Walls of varying thickness in accordance with the degree .of .expansion required for exerting evenly distributed forming pressure on the portions of the sheet located at difierent distances from the center of the article to be formed, and means to expand said inflatable member.

3. A method for forming a plurality .of individual flexible sheets of wood into an article whose outer surface is of the same configuration as the inner shape .of a separable hollow form comprising the steps of initially bending a plurality of individual superposed sheets of having adhesive "therebetween within and along the wall of the hollow form while placing them thereadjacen't in a free and unattached adjacent relationship, of expanding the plurality of sheets outwardly simultaneously against the inner surface of the rormby use of a forming pressure shape the same into a laminated azrticle having the configuration of the inside wall of the form, said 'free and unattached relations-hip of the sheets permitting relative sliding movement between them when the forming pressure is :exerted, and retaining the "forming pressure 'upon the sheets until theyadhes'ive therebetween has set, whereupon the article can be removed from. the mold in a completely assembled condition.

4. The method of forming an article to :a'fini'shed shape directlyfrom apluralityof individual flexible sheets of 'Wood which comprises; precutting a plurality of individual fiexible she'ets of wood adapted to cooperate one another to be shaped into the contour of a finished Haminated article; arranging the plurality of individual pre-cut sheets of wood with adhesive therebetween "within a hollow term in a free and unattached adia'cent relationship in :a manner that the pro-cut sheets are disposed with respect to each other in a selected layer arrangement determined by the relative sizes of the precut sheets, the size of the sheets gradually diminishing as they approach the interioriof the form, to position them in their proper layer relationship; simultaneously pressing the plurality 0f sheets outwardly against the inner .surface of the form to cause them to assume their proper relationship withrespect to one another to shape the sam'einto a laminated arZt-icle having the con; figuration of the inside surface of the form: and retaining the forming pressure upon the :sheets until the adhesive 'therebetween has set, whereupon the article can be removed from the mold .in a completely assembled condition and its finished shape.

5., A method for forming a plurality or superposed individual flex'ible sheets of wood :into an article Whose outer surface'is of the same configuration as the inner shape of a hollow form having a floating yielding pressure applying device therein adapted to communicate with a source of pressure located outside of said hollow form which consists in arranging a plurality of individual sheets. of wood veneer having adhesive therebetween Within and along the wall :of the hollow vform in a free and unattached adjacent relationship and between said floating, yielding pressure applying device and the wall of the form, and applying pressure to the sheets through the yielding pressure applying device to expand the sheets outwardly against "the inner wall of the form and dis-tribute the pressure uniform-1y throughout the engaged surfaces of the :sheets, and retaining the forming pressure upon the assembled sheets until the adhesive therebetween has set to form a laminated article.

6. A method for forming a plurality of individual flexible sheets of wood into an article whose outer surface is of the same configuration as the inner shape of a separable hollow .torm having a. floating yielding pressure applying device there-in adapted to communicate with a source of pressure located outside of said hollow form comprising the steps of initially bending a plurality of individual superposed sheets of wood having adhesive therebetweenwithin and along the wall of the hollow form whilev placing them thereadjacent in a free and unattached adjacent relationship and between said floating, yielding pressure applying device and the wall of the form and applying pressure to the sheets through the yielding pressure applying device to expand the sheets outwardly against the inner wall of the form and distribute the pressure uniformly throughout the engaged surfaces of the sheets, and retaining the forming pressure upon the assembled sheets until the adhesive therebetween has set to form a laminated article.

CLARENCE U. GRAMELSPACHER. 

